Communication standards for the next generation mobile phone called Long Term Evolution (LTE) are being considered by 3GPP (3rd Generation Partnership Project), which is a standardization organization related to mobile phone (cellular phone) technology.
An LTE network includes an Evolved Universal Terrestrial Radio Network (eUTRAN), which is a wireless network accommodating wireless terminals (User Equipment: UE), and an Evolved Packet Core (EPC: also referred to as LTE-Core), which is a core network (CN).
The wireless network (eUTRAN) is an access network, including at least one base station (referred to as eNodeB (eNB)), for connecting, to the EPC, a wireless terminal (referred to as User Equipment: UE) to be attached to the base station.
The EPC includes a Mobility Management Entity (MME), a Serving Gateway (S-GW), and a Packet Data Network Gateway (P-GW).
The MME is a control device to handle a Control plane (C-plane) for network control. The MME is connected to a base station via an S1-MME interface which is an S1 interface for the C-plane. Also, the MME is connected to a device called a Home Subscriber Server (HSS) that handles service control and/or subscriber data, via an interface (an S6a interface) for the C-plane.
The S-GW is a gateway located between the access network (eUTRAN) and the EPC, and handles a User plane (U-plane), which is packet data of user data. The S-GW is connected to a base station via an S1-U interface which is an S1 interface for the U-plane. Also, the S-GW is connected to the MME via an interface for the C-plane called “S11 interface”.
The P-GW is a gateway for connecting the UE to an external network (a user packet network) such as the Internet. The P-GW is connected to the S-GW via interfaces for the C-plane and the U-plane (S5 PMIP, etc.). Thus, the EPC includes architecture by which a U-plane packet (user data) is relayed via two nodes, the S-GW and the P-GW.
For more information, see Japanese Laid-Open Patent Publication No. 2004-64182, and Japanese Laid-Open Patent Publication No. 2004-350188.
According to the current EPC, selection of the S-GW and the P-GW for a certain U-plane is performed by the MME, which is a physical device different from the S-GW and the P-GW. The MME does not take the physical arrangement of the S-GW and the P-GW into account when selecting the S-GW and the P-GW.